An efficacious strategy for addressing problem substance use among college student drinkers is to target core risk factors. Arguably one of the most clearly documented risk factors for problem drinking among college students is impulsivity, with the relationship holding across various dimensions of impulsivity. Available evidence supports the importance of intervening with impulsivity to limit problem drinking among college students, but there are few proven treatments for any dimension of impulsivity. This notable lack may be due to the traditional view of impulsivity as an unchangeable personality trait. However, recent research suggests personality can change and is sensitive to behavior manipulation. As a result there is clear need for novel approaches targeted at core changes in the individual and their behavior patterns. Mindfulness meditation (MM) is a unique option in this direction as MM is especially useful in reducing impulsive behaviors including problem drinking, but its exact role in affecting different dimensions of impulsivity and in effecting change in problem drinking has yet to be explored. Based on evidence from recent studies, as well as our own pilot work, we hypothesize that one of the mechanisms by which MM reduces problem drinking among college students is by lessening impulsivity - moreover, the focus on changing college student problem drinking is done without any explicit focus on drinking behavior itself. The specific aims of this Stage 1 therapy development study are to: 1) modify and further develop a breathing-based mindfulness therapy (BBMT) for reducing impulsivity and problem drinking among college youth; 2) investigate the feasibility and preliminary efficacy of applying BBMT for reducing problem drinking with a pilot randomized controlled trial (RCT); 3) examine changes in impulsivity, as measured by both behavioral and self-report assessments, as one of possible mediators in the observed effect of BBMT on problem drinking. These aims will be achieved in two phases. In Phase 1 we will expand and fully develop the existing BBMT program with manuals to determine the effective treatment dosage for both problem drinking and impulsivity in an open label trial (n = 10). Using the modified treatment materials from Phase 1, in Phase 2 we will conduct a RCT comparing the effects of modified BBMT to a Supportive Counseling + Progressive Muscle Relaxation (SC + PMR) control condition (n = 36 each) on problem drinking, assessed at baseline, weeks 4 and 8, and a 3-month follow-up. Other potential mediators such as perceived stress and anxiety also will be examined in the final model. This study has great implications for reaching student drinkers who are less willing to acknowledge their drinking problems since it addresses core vulnerability (impulsivity) among at-risk students in a manner that limits stigma and may reduce resistance to change. A diverse team experienced in mindfulness, impulsivity and behavior therapy development has been assembled to conduct the proposed R34 project and prepare for a full therapy development study in the future.